A wireless communication system normally provides communication for a number of mobile devices, each of which may be serviced by a base station.
Mobile IP is a communications protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address. Mobile IP may be found in wireless environments where users carry their mobile devices across multiple access networks. For example, Mobile IP may be used in roaming between overlapping wireless systems, e.g., IP over wireless LAN (WLAN), High Rate Packet Data (HRPD), Long Term Evolution (LTE), etc. In the context of Mobile IP, a mobile device may be referred to as a mobile node.
The most recent version of Mobile IP is Mobile IP version 6 (MIPv6). In accordance with MIPv6, when a mobile node leaves one access network and connects to another access network (referred to herein as the new access network), it receives a care-of address from the new access network. The mobile node then sends a binding update to its home agent, which is at a fixed place in the Internet (e.g., at the mobile node's home network). The binding update causes the home agent to bind the mobile node's home address with its current care-of address. Packets sent to the mobile node's home address are routed to the home agent, and the home agent tunnels those packets to the mobile node's care-of address.
Proxy MIPv6 (PMIPv6) is a variant of MIPv6 where the mobile node is not involved in the signaling. PMIPv6 uses mobility access gateways in the network to proxy MIPv6 signaling on behalf of the mobile node, as the mobile node moves from one mobility access gateway to the next. The mobile node's home network includes a local mobility anchor, which is similar to the home agent in MIPv6. When a mobile node leaves one access network, it attaches to a new access network and a corresponding mobility access gateway. The new mobility access gateway sends a proxy binding update to the local mobility anchor, which binds the mobile node's home address with its current mobility access gateway. Packets sent to the mobile node's home address are routed to the local mobility anchor, and the local mobility anchor tunnels those packets to the mobility access gateway. The mobility access gateway then delivers the packets to the mobile node.